Defensins are small cationic peptides exhibiting broad antimicrobial activity that are stored in the cytoplasmic granules of mammalian neutrophils and Paneth cells of the small intestine. Neutrophil defensins have been isolated from human, rabbit, rat and guinea pig. Despite the great similarites in the sequences and the 3-D conformation of all neutrophil defensins, human defensins dimerize in solution while rabbit defensins only exist as monomers.